# Quantum Bayesian Networks

## January 24, 2019

### Qubiter (a quantum programming language) now has functional placeholders

Filed under: Uncategorized — rrtucci @ 11:04 pm

On Jan 11, just 13 days ago (by comparison, Trump’s shutdown is now 34 days old), I wrote a blog post announcing that what I call “placeholders” had been incorporated into Qubiter. Since then, my ideas about placeholders have been undergoing a Darwinian evolution culminating with an update that I uploaded today to Qubiter’s Github repo, in which I add to Qubiter, a new kind of placeholder, what I like to call “functional placeholders”. (previous types of placeholders still work). In a functional placeholder, instead of entering a numerical rotation angle $\theta$ for a quantum gate like $R_Z(\theta)$, one enters a string that includes a function’s name. Here is an example written in the Qubiter language. In the example, '-my_fun#2#1' is evaluated to -my_fun(#2, #1). Notice from the example that we delay deciding the value of all placeholders until the moment right before we run the simulator, at which time we enter the values of all the placeholders as an input to the simulator. That is the essence of placeholders.